The long-term objective of this proposal is to study the toxicity of airborne pollutants on lung cells with the use of in vitro test systems. Two such systems are proposed: 1) human upper and lower airway epithelial cell cultures; 2) rodent peripheral lung organ cultures. It is our hypothesis that the proposed test systems will be useful for determining the toxicity of airborne pollutants, individually and as mixtures, that are found in urban environments and in occupational settings at concentrations relevant to present-day exposures. These test systems will also be utilized to investigate mechanisms of respiratory cell injury caused by airborne pollutants. The specific aims are to: 1) expose human nasal and bronchial epithelial cell cultures to low concentrations of gaseous air pollutants such as ozone (O3) and sulfur dioxide (SO2) 2) expose the same two types of epithelial cell cultures within a uniquely designed exposure chamber that will allow quantitative exposure of the cells to complex airborne mixtures such as those found in ambient or environmental aerosols that contain sulfuric acid and sulfate particles and in occupational settings that contain volatile organic chemical mixtures generated during the manufacture of advanced composite materials (ACMs); 3) Utilize rodent peripheral lung organ cultures as a short-term assay system to evaluate the toxic effects of fibers and dusts generated during the manufacture of ACMs. The airborne pollutants will be tested at concentrations relevant to environmental and occupational exposures. The concentration and time duration ranges for O3 will be 0.1, 0.3, or 0.5 ppm for 1 or 3 hours; for SO2 the concentrations will be 0.5, 1 or 5 ppm for 30 or 60 minutes. Acidic sulfate-containing aerosol particles are a toxic component of polluted urban air. The role of acidity of sulfate aerosols in causing lung injury will be determined by varying the acidity of the particles. The ammonium to sulfate ratio will be varied such that the amount of free acid deposited per particle will be varied from 0 to 1000 attomoles per particle in seven equal logarithmic steps. The organic vapors generated prior to polymerization of ACMs will be studied first in a relatively simple two-component (phenol-formaldehyde) model system, than as more complex multi-component mixtures. Dusts generated during the machining and decomposition of ACMs will be evaluated in lung organ cultures. Cellular injury and tissue damage will be measured with a battery of assays to systemically examine enzymatic, metabolic, functional and structural responses, including: 1) 51Cr release, 2) 3H-leucine incorporation; 3) alteration of cellular ATP levels; 4) alteration of cellular glutathione content; 5) cell proliferation/cell kinetics; 6) loss of intercellular communication via gap junctions; 7) epithelial cell morphology.